The study will make use of existing data bases of the Eastern Cooperative Oncology Group, as well as collecting new data, to study the treatment of the elderly cancer patient. These specific areas of investigation are targeted: (1) special problems associated with cancer chemotherapy in the elderly, in particular, the identification of drugs that cause excessive toxicity in the elderly; (2) patterns of care in the elderly, in particular the extent to which elderly patients are treated on research protocols, or indeed treated at all; (3) incidence of co-morbid diseases in the elderly. The results of these studies are essential for rational treatment planning in the elderly. The research is multi-disciplinary, spanning medical oncology and biostatistics.